.container {
  position: relative;
  display: inline-block;
}

.avatar {
  position: relative;
  z-index: 1;
  overflow: hidden;
  border-radius: 50%;
}

.mask {
  position: absolute;
  top: 0;
  left: 0;
  z-index: 2;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.5);
  border-radius: 50%;
  opacity: 0;
  transition: opacity 0.2s ease-in-out;
}

.container:hover .mask {
  opacity: 1;
}

.button {
  position: absolute;
  top: 50%;
  left: 50%;
  z-index: 3;
  transform: translate(-50%, -50%);
  opacity: 0;
  transition: opacity 0.2s ease-in-out;
}

.container:hover .button {
  opacity: 1;
}
